Method and apparatus for treatment of fluids

ABSTRACT

The invention relates to a method for treatment of fluids, the invention being characterized in that ozone is generated in the medium, which ozone is exposed to UV radiation at the same time as it is being generated, so that the ozone is broken down and free radicals are obtained. The invention also relates to an apparatus in accordance with the method, which apparatus comprises an enclosure (1) provided with at least one inlet (2) and at least one outlet (3). The apparatus is characterized in that an oxidizing member (4) is arranged in the enclosure (1) and generates ozone and at the same time breaks down the ozone to free radicals.

TECHNICAL FIELD

The present invention relates to a method and an apparatus for treatmentof fluids. Fluids will in this context be understood as gases and liquidmedia as well as suspensions and emulsions.

STATE OF THE ART

In recent years, ever greater demands have been placed on theenvironment wherever man has been present. There are many reasons forthis. One is that modern man's mobility between different geographicalareas means that pathogens find fertile breeding ground for developmentof extremely virulent strains. These can give rise to serious diseasesfor which there are as yet no cures.

In hospitals, pathogens can be transmitted from one patient to otherpersons--both patients and nursing staff--and these pathogens aretransmitted further by direct contact or indirectly via instruments,clothes, food or the like. Hospital textiles are contaminated to agreater or lesser extent with pathogens. One problem is that the washingmethods are not completely satisfactory as regards removal of pathogensfrom hospital textiles. In addition, there is a need for better andsimpler methods for sterilization, on the one hand of sensitiveequipment such as, for example, endoscopy instruments and catheterswhich do not tolerate conventional sterilization methods, and, on theother hand, in operations where instruments need to be sterilizeddirectly and quickly as they may have become contaminated during surgery(the surgeon may, for example, drop special instruments, implants andthe like).

Other environments where pathogens and other types of pollution arespread and which often have problems with poor air are schools, daynurseries, food shops, kitchens, ship cabins, industrial premises andthe like, especially in poorly ventilated premises. A further problemarea is "sick houses" with, for example, radon, mould, hexamine and thelike, as well as premises which are being painted, papered, floored,etc.

Water is another area where ever greater demands are being placed bothon purity and on minimizing the environmental pollution when treatingdrinking water and waste water.

These media, and media contaminated in other ways, have createdconsiderable unrest and the need for effective decontaminationprocesses.

A number of proposals for dealing with the abovementioned problems havebeen put forward during the years, such as better ventilation, varioustypes of filters and chemicals for purification of air and water. Sincechlorine itself is a burden on the environment, methods have beendeveloped in several countries for purifying water with ozone (O₃) indrinking water installations and bathing facilities, and also ozonedissolved in water for cleaning, disinfection and sterilization ofarticles. The reaction capacity of ozone (2.07 V electrochemicaloxidation potential) is ascribed to the fact that it is a powerfuloxidant. The high chemical reactivity is coupled with the unstableelectron configuration which seeks electrons from other molecules, whichthus means that free radicals are formed. In this process, the ozonemolecule is broken down. By means of its oxidizing effect, the ozoneacts rapidly on certain inorganic and organic substances. Its oxidizingeffect on certain hydrocarbons, saccharides, pesticides, etc., can meanthat ozone is a good choice of chemical in certain processes. Acombination of ozone, oxygen, hydroperoxide and UV radiation means thatthe reaction proceeds much more quickly and more efficiently by virtueof the generation of more free radicals.

The inactivation of microorganisms with the aid of ozone and radicals isconsidered as an oxidation reaction. The membrane of the microorganismis the first to be attacked. Within the membrane/cell wall, the ozoneand the radicals destroy nuclear material insider the cell/virus/spore.The inactivation reaction in the case of most microorganisms occurswithin minutes, depending on the ozone dose and the amount of freeradicals which are formed.

In most cases, ozone is used in the form of ozone water for

removing or reducing chemicals, dyes, heavy metals, odour, anddestroying pathogens in water-purification works,

removing algae, fungus, deposits, and for reducing the use of chemicalsin water-cooling systems and heat exchanges,

treating water in pools, aquariums and fish farms,

sterilizing bottles and jars which are used in the beverage and foodindustry.

Despite its solubility in cold water, ozone is broken down (=consumed)quickly, as is the case in air, which gives a great many differentradicals and more or less stable by-products such as aldehydes, bromateand carboxylic acids. The degree of breaking down depends on the pH, thesubstance which is exposed and the temperature. Certain substances arebroken down easily by the ozone. However, the majority of substances andmolecules are oxidized more efficiently by free radicals which areformed by ozone and the media treated by ozone. Certain free radicalshave a higher electrochemical oxidation potential than ozone (2.8 V forhydroxyl radical and 2.42 for oxygen (singlet)). Examples of commonoxidants which can be formed are hydroxyl radicals (HO'), peroxylradicals (RO₂ '), (singlet) oxygen (¹ O₂), diradicals (R'--O') andalkoxy radicals (RO').

Oxidation of organic molecules is best understood on the basis of thetwo similar paths for reactions of HO', RO', RO₂ ' and ¹ O₂ radicals.Most organic chemicals which are mixed with air as gases are oxidized byHO' radicals. Aliphatic molecules give RO₂ ' radicals which can undergovarious reactions, the most significant of which is the conversion to analkoxy radical (RO') via NO. Reactions of RO' radicals are rapid andproduce new carbon radicals by cleaving or by intramolecular transfer ofH atoms. A reaction cycle of intramolecular tranfer of H atoms,formation of a new RO₂ ' radical, conversion to the corresponding RO'radical and, finally, a further intramolecular reaction can lead tohighly oxidized carbon chains.

Aromatic molecules oxidize quickly with HO' radicals, which forms carbonradicals and phenols. Singlet oxygen (¹ O₂) is important for oxidizing agreat many organic chemicals, including amino acids, mercaptans,sulphides and polycyclic aromatic hydrocarbons. These too are rapidoxidation processes.

Consequently, ozone reacts with contaminants via two essential pathways.It can react directly, as molecular ozone (O₃), by reactions which areselective. In general, activated compounds (phenol, resorcinol,salicylate), olefins and simple amines are expected to react withmolecular ozone, as are certain microorganisms.

Alternatively, ozone can react with contaminants via an indirect route,in which the free radicals, which are produced by decomposition of ozoneand by reactions, serve as oxidants. These indirect reactions of theradical type are rapid and non-selective.

Organic contaminants which react slowly with molecular ozone, such asaliphatic acids, aldehyes, ketones and aromatic hydrocarbons, react to agreater extent via the non-selective radical route. Thus, the conditionswhich break down ozone, such as UV radiation, favour indirect andnon-selective reactions where the free radicals formed are strongoxidants. In the case of air, the radical route has a predominant rolein most oxidation processes. Even in situations where the firstoxidation reaction between the ozone and contaminants takes place viathe direct route, radicals are generated so that the subsequentoxidation takes place effectively and rapidly by means of radicalreaction processes.

Since the radicals are non-selective, they can oxidize all reducedsubstances and are not limited to a specific classes of contaminants, asis the case with molecular ozone.

As has been mentioned, UV radiation favours a rapid decomposition ofozone with subsequent formation of radicals. In those cases wherecontaminants absorb UV radiation (for example, tetrachloroethylene),direct photolysis of the pollutant contributes to the degree ofoxidation.

In many apparatuses, ozone is generated by corona discharges. When a 6-7cV electron interacts with an oxygen molecule (O₂), dissociation takesplace. The oxygen atoms (O+O) which are formed are immediately combinedwith oxygen molecules to form ozone (O₃).

It is also known that UV radiation with a wavelength of approximately183 nm gives rise to ozone in air. However, it is difficult to make suchlamps adequately effective for production of ozone in the largequantities which may be needed in many cases.

A number of trials on purifying air with ozone have been carried out,such as described, for example, in the patent U.S. Pat. No. 5,186,907.The patent describes an apparatus for treatment of organic waste gaseswhich contain toxic components as organic solvents. The gases are suckedinto an enclosure by a fan and are initially exposed in the saidenclosure to a first oxidizing member, for example aUV lamp, whichcauses oxygen in the air to form ozone. The oxidizing effect of theozone means that most of the organic solution forms peroxide. Theperoxide is then irradiated by a second oxidizing member, in this case aUV lamp which emits radiation at a wavelength of 365 nm, so that theperoxide is broken down almost completely to carbon dioxide, water andinorganic gas components by oxidation. At the same time, those parts ofthe organic gas which were not oxidized by the first oxidizing memberand the ozone will be oxidized and broken down by the second oxidizingmember.

The apparatus in accordance with the above is targeted at organicsolvents such as isopropyl alcohol, where the first oxidizing memberconverts the solution to peroxide, which is then oxidized by theradiation from a UV lamp at a wavelength of 365 nm. This apparatus has anarrow scope of application, specifically for treatment of certaindefined organic solvents.

In the patent U.S. Pat. No. 5,260,036, a method of photochemicallyoxidizing gaseous halogenic organic compounds is disclosed. According tothe patent, the compounds are exposed to UV light to oxidize them intogaseous oxidation products and reacting the gaseous oxidation productswith a surface inside an oxidation chamber, where the surface a materialwhich is chemically reactive with the gaseous oxidation products inorder to produce solid reaction products incorporated in side walls ofthe chamber. This chemically sorbant internal surface material has alife of 1-3 months.

It is evident from what has been described above that ozone can be usedto good effect for purifying, disinfecting and sterilizing withincertain areas and in the case of certain substances. The use of ozonefor the purpose of obtaining free radicals therefrom should, however,considerably increase the efficiency, the scope of application and thesubstances which can be rendered safe. This procedure has not until nowbeen used effectively.

SUMMARY OF THE INVENTION

The object of the invention is to tackle the abovementioned set ofproblems with purification and disinfection of contaminated media suchas air, water and solid articles, and also disinfection andsterilization of articles in a more efficient manner than has beenpossible with previous methods and apparatuses. This is achieved bymeans of a procedure and apparatus according to the claims.

DESCRIPTION OF THE FIGURES IN THE DRAWINGS

The procedure using preferred embodiments of apparatuses according tothe invention will be described in detail hereinbelow and with referenceto the attached drawings, in which:

FIG. 1 shows a cross-section of an apparatus according to the presentinvention;

FIG. 2 shows a cross-section of a development of the apparatus accordingto the invention;

FIG. 3 shows a cross-section of a further development of the apparatusaccording to the invention;

FIG. 4 shows a variant of the apparatus and an example of the use forproduction of a sterilizing gaseous fluid for sterilization of solidarticles in a closed space; and

FIG. 5 shows another variant of the apparatus according to the inventionadapted for a liquid-state fluid.

DETAILED DESCRIPTION OF THE INVENTION

The procedure according to the present invention is as follows. Themedium which is to be treated is preferably introduced into some form ofenclosure. In the enclosure, the medium is exposed to UV radiation witha spectral distribution within the range of 180-400 nm. The wavelengthof 183.7 nm in particular converts the oxygen in the medium to ozonemolecules (O₃). The ozone molecules formed are at the same timedecomposed by radiation within the abovementioned wavelength range,especially at a wavelength of 254 nm. At the same time, the O₂ formed isbroken down to form atomic oxygen. In order to increase the efficiencyduring generation of free radicals, in particular HO' radicals, oxidesare added as catalysts. In order to obtain a greater amount of ozone andconsequently more free radicals, further ozone is generated before themedium is irradiated.

An apparatus which is based on the abovementioned method is shown inFIG. 1. The apparatus is designed as an enclosure 1 with at least oneinlet 2 and one outlet 3. An oxidizing member 4 is arranged in theenclosure 1, in the preferred embodiment a number of UV lamps with aspectral distribution within the range of 180-400 nm. The lamps 4 arepreferably placed in such a way that the entire area 5 around the lamps4 in the enclosure 1 is illuminated with approximately the sameintensity. The inner walls of the enclosure 1, at least in the area 5around the lamps, are arranged so that they provide for a goodreflection of the light from the lamps 4. A member 7 for circulating theair, for example a fan, is arranged at the outlet 3 in order to lead theair which is to be treated through the apparatus 1.

A number of catalyst 8 are preferably also arranged in the enclosure inthe area 5. They can be attached, for example, in a suitable manner tothe reflecting inner wall of the enclosure. In the preferred embodiment,the catalyst comprise metal and/or metal oxide, such as noble metals,aluminum oxide, titanium oxide, silicon oxide and mixtures thereof.

The functioning is as follows. When the apparatus is to be used, thecurrent to the lamps 4 is switched on and the fan 7 beings to rotate.The fan 7 sucks air into the inlet 2, which air flows through theenclosure 1 and through the area 5 where the lamps expose the air to UVradiation. Due to that the walls in the area 5 of the lamps arereflective, the air is exposed to the UV radiation to a higher degree,and thus increasing the efficiency. The spectral distribution of the UVlamps means that ozone molecules (O₃) are generated by the oxygen in theair, and especially by radiation at a wavelength of 183.7 nm. At thesame time, radiation is generated by the lamps within a wavelength rangeof 245-400 nm, within which wavelength range the ozone molecules arebroken down to oxygen and free radicals, and contaminants to freeradicals. Of particular importance are the wavelength of 254 nm and alsothe wavelength of 364.9 nm, at which increased efficiency in thegeneration of free radicals is obtained. The catalysts, which are placedin the area 5, render the process more effective by increasing theamount of free radicals per unit of time. By virtue of theirsusceptibility to oxidation, the free radicals start a chain reactionwith the contaminants in the air. The free radicals, and to a certainextent the ozone, effectively break the bonds between the atoms in themolecules which contaminate the air. Microorganisms such as, forexample, pathogens are rapidly killed off, and from organic andinorganic matter new free radicals are formed which are more or lessreactive. The final products are in the main water vapour, air andcarbon dioxide. This embodiment of the apparatus is primarily conceivedfor purification of air, for example in office premises, schools,gymnasiums, smoking rooms, cabins, toilets.

FIG. 2 shows a development of the apparatus according to FIG. 1. In FIG.2, the same components have the same reference numbers as in FIG. 1. Inthe apparatus according to FIG. 2, a section 1I of the enclosure 1 hasfurther been connected to the inlet end 2 thereof. The new section 1I isarranged with an ozone generator 9 of a suitable type. In the preferredembodiment, the ozone generator 9 is a small dark-discharge unit. In thegap between the electrodes, silicon or similar powder is packed or ismixed with the dielectric material (ceramic), by which means the poweris increased and the generator can be made small in size. Other ozonegenerators can also be conceived, such as electrode plates with acertain air gap where discharges are generated between the plates, andalso UV lamps which emit at a certain wavelength. By increasing theamount of ozone, the power is considerably increased. The ozone which isformed by the ozone generator reacts on the one hand directly with thecontaminants in the air and is decomposed, and on the other hand isdecomposed by the UV lamps to form free radicals in large quantity. Thisembodiment is primarily conceived for purification of air in large areasand/or areas which are heavily contaminated, such as industrialpremises, smoke-damage premises, stables, etc.

FIG. 3 shows a third embodiment of the apparatus according to theinvention. In this embodiment, a section 1II is placed downstream of theoutlet 3 to the apparatus according to FIGS. 1 and 2. The section 1II isarranged with a filter 10. The filter 10 consists of porous oxidicceramics, aluminum oxide, calcium hydroxide, magnesium hydroxide andactive charcoal and carbonate. The filter is provided with a number ofpassages 11, in the preferred embodiment slightly inclined with respectto the direction of flow F in order to increase the contact surfacebetween the filter and the air. The apparatus with the filter isprimarily conceived for use in premises with organic gas, where thefinal products may be unidentifiable, or where there are chlorinatedsolvents, alcohols, ketones, aromatic compounds, dioxins, hexamine(hexamethylene tetramine), formaldehyde, ammonia, pesticides andherbicides. The abovementioned filter effectively deactivates thesefinal products, and only water vapour, carbon dioxide and air escapefrom the outlet.

Since both the ozone and in particular the free radicals areshort-lived, continuous generation of ozone and free radicals isnecessary. The speed of rotation of the fan and consequently the flowrate are adapted to the amount of ozone which is produced in order toobtain an optimal functioning of the apparatus and in order to ensurethat no untreated ozone escapes into the environment. The apparatus canbe arranged, for example, with a timer which switches the apparatus onat specific time intervals. The flow of air through the apparatus alsohas the object of cooling the electronic components and warming thefilter 10 to increase its efficiency.

By virtue of the modular system with different sections, it is simple toadapt the apparatus to the conditions in which it is to operate. Thus,it is possible to obtain apparatuses with everything from one section 1with UV lamps to a serial connection of several sections 1 arranged oneafter the other, ozone generator 9 and filter 10. The fan 7 is alsoarranged on a section 12. FIG. 3, and it thus forms a modular unit too.The sections can then be mounted on a suitable holder ledge 13, FIG. 3,which is arranged on a suitable support. The holder ledge contains theelectrical connection, circuit breaker and optional timer. Theelectrical connections between the sections and the holder ledge 13 arepreferably of the plug-in type. Great flexibility and ease of servicingare obtained in this way since only the faulty section needs to beexchanged or repaired and it is not necessary to dismantle the entireapparatus.

FIG. 4 shows an example of the scope of application and also theadvantages of the modular system, for example for sterilizing articlesetc., such as operating instruments and catheters which it has not beenpossible to sterilize, with optimal results, using conventional methods.FIG. 4 shows a cabinet 20 or other well-defined enclosure provided witha door, hatch or similar (not shown) which seals it tight when it isclosed. The articles which are to be treated are placed in the cabinet20, for example on perforated shelves 21. It is also conceivable to useholders specially adapted for the articles which are to be treated. Whatis important is that the air with free radicals can circulate freelyaround the articles. Air is drawn in through an inlet 22 provided with aclosable valve 23. Connected to the inlet 22 is in the first place asection 1I with an ozone generator which converts oxygen in the incomingair to ozone molecules. Downstream of the section 1I with the ozonegenerator, as viewed in the direction of flow, there is a second section1 with UV lamps and catalysts. The radiation from the UV lamps formsozone and breaks down the latter and the previously formed ozonemolecules to give free radicals which flow in large quantity out intothe cabinet and sterilize the articles which are placed on the shelves21. At the upper edge of the cabinet there is a fan section 12, and alsoa section 1II with filter arranged at an outlet 24, which outlet isprovided with a closable valve 25. The fan section 12 generates a flowof air from the inlet 22, through the cabinet and out through the outlet24. The cabinet is preferably provided with a member which locks thedoor when the apparatus is in operation, and which indicates this, forexample by means of a lamp. The cabinet is also provided with a timecontrol for the apparatus, adapted to the size of the space and to thesize and shape of the articles which are to be treated. The cabinet 20can be different sizes depending on what is to be treated. It may beadapted, for example, for disinfecting and sterilizing of textiles inthe form of operating gowns and the like, which are used in hospitals,the pharmaceutical industry, abattoirs, the electronics industry, etc.

The procedure described above and the apparatus can of course also beused to purify contaminated water, on the one hand, and on the otherhand to use water enriched with free radicals for cleaning, disinfectingand sterilizing of instruments, electronic devices, biomaterial andtextiles, for example. FIG. 5 shows an example of the use of the presentinvention for treating water, i.e. decontaminate water or enrich waterwith free radicals. In this embodiment, one or more sections 1 with UVlamps are placed in the water flow 30. Arranged in a suitable mannerupstream of the sections 1 is a connection 31, to which connection 31 asection 1I with ozone generator 9 and a fan section 12 are joined.Between the connection 31 and the water inflow 30 there is some form ofnonreturn valve. When circulation of the water through the apparatus isrequired, i.e. when there is no external flow through the apparatus, apump 32 is used. The water which flows through is first exposed to ozonefrom the ozone generator 9, where the ozone is forced down into thewater by the fan 7. Ozone is thus added continuously to the water, whichozone water is then immediately irradiated with UV light in order todecompose the ozone and obtain free radicals. When the water is heavilycontaminated, or when large amounts of free radicals in the water isneeded, an ultrasonic device (33) is placed at the water inflow. Highamplitude ultrasonic waves generate free radicals and breakcontaminators. And in the same way as with the apparatus describedabove, the apparatus for purifying water can be combined in a number ofways by virtue of the modular system.

The procedure according to the present invention permits a moreeffective purification, disinfection and sterilization in many areas ofapplication and for many organic and inorganic substances, contaminantsand microorganisms in air, in water and on solid objects. Examples ofadvantages are low energy consumption, no heating of objects, air orwater, no chemicals/cleaning agents, small size of the unit, no toxicby-products, long service life, low maintenance and many applications.

It will be understood that the procedure and the apparatuses accordingto the present invention are not limited to what has been describedabove, and can instead be modified within the scope of the patent claimswhich follow.

I claim:
 1. A method for treatment of fluids, comprising:providing aflow of the fluid in an enclosure between an inlet and an outlet of saidenclosure; generating ozone in the fluid flowing in the enclosurethrough the use of at least one ozone generating means; immediatelyexposing the generated ozone to UV radiation at the same time as it isbeing generated, thereby breaking down the ozone in order to obtain freeradicals to destroy contaminants; and adding oxides in the enclosurethrough the use of catalysts in order to increase the amount of freeradicals.
 2. The method according to claim 1, wherein the UV radiationwhich is emitted for breaking down the ozone and contaminants has awavelength of 245 nm-400 nm.
 3. The method according to claim 2, whereinthe UV radiation which is emitted for breaking down the ozone has awavelength of 254 nm.
 4. A method for treatment of fluids,comprising:providing a flow of the fluid in an enclosure between aninlet and an outlet of said enclosure; generating ozone in the fluidflowing in the enclosure through the use of at least one ozonegenerating means; immediately exposing the generated ozone to UVradiation at the same time as it is being generated, thereby breakingdown the ozone in order to obtain free radicals to destroy contaminants;and adding oxides in the enclosure through the use of catalysts in orderto increase the amount of free radicals; wherein the fluids are selectedfrom the group consisting of water and air.
 5. An apparatus fortreatment of fluids, the apparatus comprising:an enclosure provided withat least one inlet and at least one outlet, at least one ozone generatorand at least one UV radiator arranged in the enclosure such that theozone generator generates ozone and at the same time the UV radiatorbreaks down the ozone to free radicals; and catalysts arranged close tosaid ozone generator and said UV radiator for increasing the amount offree radicals; wherein a filter is placed downstream of the UV radiator,and wherein the filter consists of oxidic porous ceramics with a numberof passages.
 6. The apparatus according to claim 5, wherein the filteralso includes active charcoals and carbonate.
 7. An apparatus fortreatment of fluids, the apparatus comprising:an enclosure provided withat least one inlet and at least one outlet, at least one ozone generatorand at least one UV radiator arranged in the enclosure such that theozone generator generates ozone and at the same time the UV radiatorbreaks down the ozone to free radicals; catalysts arranged close to saidozone generator and said UV radiator for increasing the amount of freeradicals; and a closed space with an inlet and outlet, in that at leastone ozone generator is arranged in the inlet, in that said at least oneUV radiator is arranged downstream of said at least one ozone generator,and in that a flow member is arranged in the outlet for sterilizingsolid objects wherein the outlet is arranged with an oxidic filter. 8.The apparatus according to claim 7, wherein the filter consists ofoxidic porous ceramics with a number of passages.
 9. The apparatusaccording to claim 8, wherein the filter also includes active charcoalsand carbonate.